is behind the deadly attack.whether they are foreign or domestic terrorists. and why. president obama plans to visit boston on thursday to attend an interfaith service in honor of the victims. hundreds of people gathered tonight on the boston common for a vigil to honor the victims. the crowd sang songs and lit candles. they held signs that read - "peace here and everywhere." mourners tonight said, the people of boston would not be afraid. there was a heavy military presence on the boston common. with dozens of national guard troops standing by. it has been reported and that this backpack/bag is part of the bomb. and that shrapnel became air born. nails were inside of the pressure cooker to become shrapnel. you can see the lettering on that the fbi is processing these items in a laboratory. they will try to track this down and hopefully the suspects will be able to be found. this is heavy-duty metal. that became a weapon and it was meant to harm humans. grant lodes, kron 4 numeronews >> a bay area boy was at the is scheduled to undergo another surgery tomorrow. he was wounded in the blast.